Spotted hyenas hunt alone to up survival rates

Published: Thursday, July 17, 2008, 11:00 [IST]

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Washington, July 17 : New research from a Michigan State University doctoral student suggests that spotted hyenas, animals that live together in large societies, hunt for food alone because it increases their survival rates.

Jennifer Smith, a student in the Department of Zoology, says that spotted hyenas know the value of living together in cooperative societies as well as of hunting alone.

"Although spotted hyenas do cooperatively hunt, there is a large cost for doing that. This cost is feeding competition within their own group," Jennifer, who did her research at the Masai Mara National Reserve in Kenya, says in the study report published in the journal Animal Behaviour.

She says that there is a well-established hierarchy in the social groups formed by hyenas, and it is the animals that are higher up on the totem pole that usually get to eat when a kill is made.

She says that spotted hyenas do join forces to protect themselves from danger, and their food from their natural enemies like the lion and neighbouring hyenas.

The researcher concedes that it should be easier for spotted hyenas to catch prey when they do so in teams.

"Although spotted hyenas are 20 percent more likely to capture prey with one or more members of their social group, cooperative hunting results in multiple new competitors showing up because former allies quickly turn into noisy competitors once the kill is made. So it's the individual, especially if he or she is low in the hierarchy, that suffers a cost for having group members at that prey," she says.

Jennifer's research paper even highlights the fact that more than a million years ago spotted hyenas were solitary scavengers.

"My research shows because there is this cost of competition, that spotted hyenas retained this ability to remove themselves from the larger social group to hunt," she says.

Jennifer describes this phenomenon as fission-fusion dynamics, wherein members of the same society repeatedly split up from the group (fission), and then reunite (fusion).

"Human societies exhibit fission-fusion dynamics. For example, we repeatedly depart from our loved ones in the morning and then rejoin them in the evening," she says. She says that just like humans, spotted hyenas frequently leave one another but rejoin on a regular basis to maintain social relationships, especially with family members.